<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .bar {
        color: yellow !important;
    }

    .foo {
        color: blue !important;
    }
</style>

<body>
    <span class=" foo bar" style="color:red">hello</span>
</body>

</html>